A highhyphen;impedance voltage measuring system is described. The system is intended for longhyphen;term, highhyphen;resolution, highhyphen;accuracy measurements from highhyphen;impedance sources or sources which are easily polarized. For input voltages of 1hyphen;V magnitude, the overall accuracy is better than 0.1 mV and the resolution is 30 mgr;V (noise limited). The input impedance is above 2times;1014OHgr; and the input bias current is 14 fA. A flexible scanning channel selector allows measurements from up to eight signal sources in parallel, a lowhyphen;cost calculator provides onhyphen;line analytical processing of measurement data, and a dynamic variable zero suppression unit makes longhyphen;term recording of signal variations down to the resolution level possible.
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